Really scratching my head on this one. I have a 92 Moomba. When I put it in the garage two weeks ago it was fine. Took it out last weekend and noticed some loss of power and what felt like a surging in speed at higher rpms (tach wasn't jumping around but it felt like it would catch and take off for a second then slow back down). When I tried to pull someone out of the water I got sluggish response and the boat was shaking pretty violently. At the time there weren't any noises coming from the engine/transmission area.

Took it out and the prop looked fine so I thought maybe I go some bad gas. Did the fuel thing, Sta-bil, changed the fuel filters, had the carb cleaned out, ect. Tried it again. This time it seemed better but I was still getting the surging at higher rpms and had lost about 7 mph of top end. Next day I put it in and when I was pulling away from the ramp I noticed a knocking sound coming from the transmission area when it was in gear.

I pulled the transmission last night and when I spin the shaft I don't hear any knocking or unusual noise. It could still be the tranny but I was also wondering if anything in the clutch could be causing this problem. Any thoughts out there?